Forced and self-inflicted sleep loss have reached epidemic proportions in western industrialized populations, costing billions of dollars in lost productivity and creating hazardous conditions on our roadways, in our skies and in our hospitals. Unfortunately, there is no simple quantifiable marker that can detect excessive sleepiness in a subject before the sleepiness results in a serious accident. To be effective, a marker for sleepiness should be responsive to increasing levels of sleep debt and should only be activated by periods of waking that are followed by compensatory increases in sleep time (sleep homeostasis).
A biomarker that can distinguish between subjects who are awake and excessively sleepy and subjects who are awake and well rested has not been identified. Thus, there is a need for a readily accessible biomarker that is responsive to sleepiness in humans.